EXHIBIT 21 SUBSIDIARIES OF REGISTRANT -------------------------- Place of Percentage of Voting Name of Subsidiary Organization Securities Owned - ------------------ ------------ ---------------- First Financial Bankshares of Delaware 100% Delaware, Inc. First Financial Investments, Inc. Texas 100% First National Bank of Abilene Texas 100%* Abilene, Texas Hereford State Bank Texas 100%* Hereford, Texas First National Bank, Sweetwater Texas 100%* Sweetwater, Texas Eastland National Bank Texas 100%* Eastland, Texas The First National Bank in Cleburne Texas 100%* Cleburne, Texas Stephenville Bank & Trust Co. Texas 100%* Stephenville, Texas San Angelo National Bank Texas 100%* San Angelo, Texas Weatherford National Bank Texas 100%* Weatherford, Texas * By First Financial Bankshares of Delaware, Inc. All subsidiaries are included in the consolidated financial statements of First Financial.